A steady state model for marine hydrate formation: Constraints on methane supply from pore water sulfate profiles
Bibliographic record
Abstract
We develop a steady state model to describe the formation of hydrate below the seafloor. The model includes the sulfate reducing zone (SRZ), which permits sulfate measurements to be used in conjunction with chloride data to better constrain the supply of methane at hydrate locations. The steady state model is applied at Ocean Drilling Program Site 997 to resolve the methane source at the Blake Ridge. Sulfate measurements rule out a shallow source of methane directly below the SRZ because the predicted sulfate concentration overestimates the measurements by a factor of 2 or more. Although a deep source of methane reproduces the main features of the sulfate and chloride data when the upward fluid velocity is 0.25 mm yr−1, the deep source fails to reproduce the increased freshening observed between 200 and 450 m below seafloor. We find that an in situ methane source (located in the lower part of the hydrate stability zone) together with an incoming methane bearing fluid at 0.23 mm yr−1 gives the best fit to both the sulfate and chloride data. In addition, the predicted sulfate profile indicates that anaerobic methane oxidation is the primary pathway of sulfate depletion at the Blake Ridge.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".